Philosophy / Natural Theology • Existence of God • Advanced
Argument from Moral Knowledge
Primary question: Even if objective moral facts exist, why should we trust that our moral faculties reliably track them?
Argument map
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Common mistakes
Don't say
Confusing this epistemological argument with the moral ontology argument that God is needed to ground moral facts' existence.
Instead
Recognize this argument grants moral facts for the sake of argument and asks specifically about reliable access to them.
Don't say
Assuming Street's dilemma alone refutes all non-theistic moral realism.
Instead
Engage seriously with Enoch's third-factor and Wielenberg's brute-fact responses, which many philosophers regard as live options.
Don't say
Treating moral disagreement as proof there is no reliable access at all.
Instead
Distinguish disagreement about contested applications from broad convergence on core moral prohibitions.
What would change my mind? — Christian position
A fully satisfying naturalistic account explaining why evolutionary and truth-tracking pressures would reliably converge, without ad hoc appeal to convenient overlap, would remove much of this argument's force.
What would change my mind? — Skeptical position
A demonstration that our apparent moral knowledge is far less reliable or convergent than assumed, reducible entirely to variable cultural or evolutionary artifact, would undercut the premise that reliable access exists at all.
Why does this matter?
This argument matters because it shifts natural theology's engagement with ethics from the classical question of what grounds moral facts to the arguably more pressing epistemological question of why we should trust our access to them, engaging directly with a live and technical debate in contemporary metaethics.
For further study
Primary and secondary sources on both sides of this question. Reading the strongest opposing case is part of the work, not a concession.
A Darwinian Dilemma for Realist Theories of Value — Sharon Street
The originating statement of the evolutionary debunking challenge to moral realism.
Taking Morality Seriously: A Defense of Robust Realism — David Enoch
Develops robust non-theistic realism and the third-factor response to Street.
Robust Ethics: The Metaphysics and Epistemology of Godless Normative Realism — Erik Wielenberg
The leading systematic non-theistic reply grounding moral knowledge in brute self-evident truths.
Finite and Infinite Goods: A Framework for Ethics — Robert Adams
Develops a theistic framework addressing both moral ontology and epistemology.
Has Nietzsche Defeated Ethics? — Mark Linville
Argues theism better explains reliable moral cognition than naturalistic alternatives.